Proceedings of the Polytechxic Association. 791 



generated by water percolating into the heated interior ; the gene- 

 ration of other gases by chemical action and electrical action. What- 

 ever the cause, it "svas contended by several, that it must be similar 

 to that which produced volcanic eruptions. 



Mr. J. K. Fisher suggested that countries where earthquakes most 

 prevail should have buildings constructed of iron. 



Mr. Dudley Blan chard stated that quite a number of iron buildings 

 had been constructed in this city, for South America, and were made 

 strong for the purpose of resisting earthquakes. 



Professor P. Vanderweyde remarked that experience has proved 

 that light buildings are better than heavy ones in case of an earth- 

 quake. A heavy building is top-heavy and will come down very 

 easily. That iron buildings would be better than wooden ones is 

 very doubtful. There are two kinds of earthquakes, the slow upheav- 

 als and the rapid upheavals. Slow upheavals are continually taking 

 place on the coast of Norway, and at Lower California the land has 

 risen one foot out of water, and at Jersey a descent has taken place. 

 Also, in Europe, in Holland and Belgium. The cause of tliis is pro- 

 bably due to the deposit at the bottom of the ocean carrying down a 

 larger amount of alluvium, and causing a strain on the bottom of the 

 ocean, which is felt at weaker points, as at Jersey and other places, 

 producing elevations. The slow upheavals prevail over a larger range 

 of surface than the rapid. When we consider the earth's crust, which 

 is very thin, and the interior to be very hot, and when we see how 

 water penetrates mountain ranges, is it to be wondered at that water 

 should exert a pressure which would be continually increasing until 

 it showed itself at the weakest point of the crust, as has been illus- 

 trated in the recent South American earthquake. The lava is pressed 

 out by the pressure of the steam. The most natural explanation is to 

 be found in the penetration of water into the interior of the earth, and 

 causing steam to form, which shows itself in volcanoes and earth- 

 quakes. All of these earthquakes and volcanoes are near water, and 

 it has been proved that these sudden convulsions of the earth are more 

 numerous and violent during a heavy rain. 



It has been a question among philosophers whether the temperature 

 increases as we go down into the earth. In some localities we have an 

 increase of one degree Fahrenheit for every sixty feet. Xow, does this 

 increase hold good as we descend into coal mines. In England there is 

 a regular increase in the mines there, but may not this be due to the 

 laborers working, there. But it has been proposed to try if this increase 



